This LED added to the robot's head enables better interaction with humans because they can see when the robot is saying something.
This was my latest improvement with the robot. This modification was extremely easy to do because the robot's audio amplifier circuit is mounted behind the face. All I had to do was add an LED across the wires that are connected to the robot's speaker. As Salvius explains in the video the purpose of this LED is to allow people to see when the robot is saying something. I thought of this after re-watching a video I had made where the robot sang Mr. Roboto and I realized that it was extremely difficult to tell if the robot was even turned on in the video. Hopefully this will be a big improvement. It is ironic that in the past I have made sarcastic remarks about robots that use lights for mouths because I thought they were useless. Looks like I was mistaken!
Now that I have installed the LED I have thought of another purpose for it. The LED could aid in self-recognition for the robot. If I had the robot say something like "Scanning for reflection" it could use its camera to look for the specific pattern that the LED blinks when it says that phrase.